1. Field of the Invention
The present invention relates to a developing roller used in an electrophotographic image forming apparatus, such as a copying machine and a laser printer, and an electrophotographic process cartridge and electrophotographic image forming apparatus which are provided with the developing roller.
2. Related Background Art
A contact development method in which a developing roller having an elastic layer is brought into contact with a photosensitive drum for development is proposed as a development method in which an electrostatic latent image on a photosensitive drum is visualized with a toner.
The developing roller used for contact development is brought into contact with a contact member while conveying a toner. Therefore, when the surface of the developing roller has strong tackiness, the conveyed toner may remain attached on the developing roller. The toner attached to the developing roller surface in this manner may degrade gradually by subsequent repeated contact of the developing roller and the photosensitive drum, and finally melted and adhered to the developing roller surface, causing filming.
As measures against such toner filming, Japanese Patent Application Laid-Open No. H09-062086 proposes a developing roller with an elastic layer that has good charging properties for toner and suppresses filming by sprinkling and attaching inorganic particles having release properties for toner onto the surface of the elastic layer.